Cairo is an agglomeration of half a dozen cities, the earliest of which came into existence 2500 years after ancient Memphis , the first capital of pharaonic Egypt, was founded (c.3100 BC) across the river and to the south. During the heyday of the Old Kingdom, vast necropolises developed along the desert's edge as the pharaohs erected ever greater funerary monuments, from the first Step Pyramid at Saqqara to the unsurpassable Pyramids of Giza . Meanwhile, across the Nile, there flourished a sister-city of priests and solar cults known to posterity as Ancient Heliopolis .

It took centuries of Persian, Greek and Roman rule to efface both cities, by which time a new fortified town had developed on the opposite bank. Babylon-in-Egypt was the beginning of the tale of cities that culminates in modern Cairo, the first chapter of which is described under "Old Cairo". Oppressed by foreign overlords, Babylon's citizens almost welcomed the army of Islam that conquered Egypt in 641. For strategic and spiritual reasons, their general, Amr, chose to found a new settlement beyond the walls of Babylon - Fustat , the "City of the Tent" (see "Old Cairo"), which evolved into a sophisticated metropolis while Europe was in the Dark Ages.

Under successive dynasties of khalifs who ruled the Islamic Empire from Iraq, three more cities were founded, each to the northeast of the previous one, which itself was either spurned or devastated. When the schismatic Fatimids won the khalifate in 969, they created an entirely new walled city - Al-Qahira - beyond this teeming, half-derelict conurbation. Fatimid Cairo formed the nucleus of the later, vastly expanded and consolidated capital that Salah al-Din (Saladin) left to the Ayyubid dynasty in 1193. But their reliance on imported slave-warriors caused power to ebb to these Mamlukes, ushering in a new era.

Mamluke Cairo encompassed all the previous cities, Salah al-Din's Citadel (where the sultans dwelt), the northern port of Bulaq and vast cemeteries and rubbish tips beyond the city walls. Mamluke sultans like Beybars, Qalaoun, Barquq and Qaitbey erected mosques, mausoleums and caravanserais that still ennoble what is now called "Islamic Cairo". The like-named page of this section relates their stories, the Turkish takeover, the decline of Ottoman Cairo and the rise of Mohammed Ali, who began the modernization of the city. Under Ismail, the most profligate of his successors, a new, increasingly European Cairo arose beside the Nile (see "Central Cairo"). By 1920, the city's area was six times greater than that of medieval Cairo, and since then its residential suburbs have expanded relentlessly, swallowing up farmland and desert. The emergence of this Greater Cairo is charted under "Gezira and the West Bank" and "The northern suburbs".